The etiology of tumors of the prostate will be studied using virologic, serologic, molecular, and cell culture techniques. Attempts will be made to detect herpesviruses or virus precursors (i.e. antigens or nucleic acids) in cells cultured from prostatic tumors. Identification and characterization of virus material found will be accompanied by determination o the immune status of the cancer patient to the foreign substance. Efforts will be directed to determine whether there is regular association of herpes simplex, cytomegalovirus, or their precursors with the tumors being studied.